350. Intersection of Two Arrays II

iven two arrays, write a function to compute their intersection.
Example:Given nums1 =[1, 2, 2, 1], nums2 = [2, 2], return [2, 2].
Note:

• Each element in the result should appear as many times as it shows in both arrays.
• The result can be in any order.

Follow up:

• What if the given array is already sorted? How would you optimize your algorithm?
• What if nums1's size is small compared to nums2's size? Which algorithm is better?
• What if elements of nums2 are stored on disk, and the memory is limited such that you cannot load all elements into the memory at once?

class Solution {
public:
    vector intersect(vector& nums1, vector& nums2) {
        map m = map();
        vector r = vector();
        for(int i=0;i 0){
                r.push_back(nums2[i]);
                m[nums2[i]]-=1;
            }
        }
        return r;
    }
};